The present invention relates to a gas turbine, and more particularly, a gas turbine having means for effectively cooling with atomized water a portion of compressed air for cooling an inlet part of the turbine.
Generally in connection with gas turbines, it is known that the operation efficiency of the turbine can be improved by raising the temperature of the driving fluid at the turbine inlet, and it is widely practiced in the today art to obtain a high temperature of the driving fluid at the turbine inlet so as to enhance the turbine efficiency.
However, by raising the temperature at or about the turbine inlet, it tends to occur that heat-resistant members disposed about the turbine inlet undergo a lowering in strength or a thermal stress, whereby it is likely that the use life of various devices at or around the turbine inlet is adversely affected. In view of this, it has already been proposed and operated in actuality to cool a part of the gas turbine around its gas inlet by a portion of the compressed air supplied from a compressor of the gas turbine. To increase the amount of the compressed air for cooling, however, is prone to accompany a sacrifice of the operation efficiency of the turbine, so that the use amount of the cooling compressed air should preferably be limited to an effective minimum value. Then, in order to suppress the use amount of the cooling compressed air, it is advantageous to cool the air.
As means for cooling the compressed air for cooling, such a method has already been reduced to practice which makes use of a cooling device provided separately of the gas turbine. A more effective method will be to effect the cooling by jetting water inside the casing of the gas turbine.
In the case of the former of the above two methods of cooling, the arrangement of the cooling device and associated piping tends to be complex and the pressure loss through the piping tends to be disadvantageously great.
In the case of the latter, then, it is likely that water becomes attached to various members and devices around the turbine inlet to give rise to generation of cracking due to a thermal impact, so that it in this case is important to effectively cause a large amount of water to be vaporized in a limited space within the turbine casing.